Unable to search for Assignee using Email Address

Issue Summary

Cannot search for a user in the Assignee field using their email address.

Steps to Reproduce

1. Ensure the user has Assignable user permission
2. Ensure you've Browser Users and groups, Assign issues permission
3. Search for the user with the email address in the Assignee field.

Expected Results

The user account should populate

Actual Results

You'll see an option to invite the user.

Workaround

Search for the user with the Display name.